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Fluid

Fluids are essential to us. Water fills the spaces in and between our cells as well playing a vital role the digestion and absorption of all the food we eat. Fluids also help to keep our body temperature within safe limits.

How much fluid do we need?

We need to make sure that our bodies stay hydrated, especially in hot weather, when exercising or playing sport. The amount needed varies according to your age, size, the weather and how active you are. Fluid comes from all we drink as well as many everyday foods (for example, watermelon and lettuce have a high water content).

So how much should we be drinking to stay hydrated? As a rough guide, adults should aim for 1.5 – 2L (6-8 cups) of fluid each day and children 1 – 1.5L (4-6 cups). This includes all drinks, including those listed below, and water. If you are exercising or playing a lot of sport you will need more. The best test that you are adequately hydrated is that you go to the toilet regularly and your urine is a pale yellow colour – if it is dark yellow you are not drinking enough water while if it looks like water, you are having too much fluid.

Fluids we commonly drink

Water. In New Zealand, tap water is cheap, readily available and doesn’t contain any kilojoules. It is the best liquid for hydrating your body.

Fruit juices usually have as much sugar as soft (fizzy) drinks, so should not be relied upon for re-hydrating. Aim for only one or two glasses of fruit juice each day.

Soft drinks, energy, sports and powdered drinks, and cordials all contain sugar and very little else in the way of nutrients. They are best reserved on an occasional basis, especially if you are watching your weight, as they are very high in energy (kilojoules/calories).

Milk and water are recommended as the best drinks for children. Milk contains valuable nutrients – calcium, protein, vitamins and minerals – and because it has a low glycaemic index (GI) it is filling. Low-fat or reduced-fat options are suitable for children older than two years of age. Flavoured milks still contain loads of beneficial nutrients but are higher in sugar than ordinary milk – check the label and choose the one that is lowest in fat and sugar.

Tea and coffee are popular drinks for many people, both for taste and the fact they are low in kilojoules/calories (before you add milk and sugar). Black and green teas and coffee all contain antioxidants beneficial for our health. Both tea and coffee contain caffeine, which stimulates the central nervous system. Coffee can have a dehydrating (diuretic)effect though, so is not a suitable drink when rehydrating before or after exercise.

Alcohol has a strong dehydrating effect, so should not be considered part of your daily fluid intake.

Tips for drinking plenty of fluids

Water and milk are the best drinks to offer children

Keep a jug of water in the fridge so that chilled water is easily available to all the family. Flavour with slices of lemon or lime.

When away from home, take a bottle of water with you

Keep juices and fizzy drinks for special occasions, not everyday.

When drinking alcohol, have water as well to counter alcohol’s strong dehydrating effect.